The poem begins with a—seemingly—rebellious act. A girl named Heidi shows up at school with a mohawk. The sides of her head are shaved and dyed blue. The hair on the “crest” of her head is gelled up into sharp, black spikes. The word “crest” is a metaphor: it compares Heidi’s hair to a mountain range, with its spiny peaks, or to the tuft of feathers or hair that some animals have on their heads.
As the speaker describes her spiky haircut, the poem’s language itself becomes sharp, with hard alliterative /c/ sounds in “clipped” and “crest.” (Those sharp sounds are balanced out by a series of softer /s/ sounds, as in “sides,” which gives these lines their own peaks and valleys: like Heidi’s haircut, the lines rise and fall, with sharp peaks and soft valleys.)
The mohawk is a symbol of punk culture. Punk music is fast, aggressive, and rebellious; punk culture is similarly anti-authoritarian, even subversive. It thrived as a subculture during the 1980s in England, where the poem is likely set. And it terrified parents and authority figures—like the teachers at Heidi’s school. They evidently see Heidi’s mohawk as a rebellious gesture, a protest against their authority. And so they send her “home from school.” In other words, they kick her out simply for having a new hairstyle. This decision seems a bit arbitrary—and no justification is given for it in the poem’s first five lines.
As a result, the speaker seems a little bit impatient. The speaker is eager to figure out why the school felt like this punishment was necessary. All of the poem’s first five lines are enjambed—even line 5, which closes the stanza. As a result, the lines spill urgently down the page. It feels like the speaker is rushing through these opening lines, trying to get to the point. And these enjambments thus build up a sense of anticipation in the reader: the reader also feels rushed, feels like they want to figure out why the school kicked Heidi out.
The poem is written in free verse: it does not have a set meter or rhyme scheme. (However, there is a slant rhyme based on the assonance between “blue” in line 1 and “school” in line 5.) The poem’s free verse is not particularly radical or challenging. Its lines are all more or less the same length; they tend to have about six syllables apiece.
This fits with the speaker’s general self-presentation. The speaker uses simple, straightforward language without a lot of poetic flourishes—and the speaker also employs a simple, straightforward form. This makes the speaker feel like an ordinary person. As the speaker narrates the poem’s events, it seems like the speaker is just another person living in Heidi’s community, observing the circumstances of her life.